import string
import random


def get_random_string(length=12):
    """
    Return a generated random string.

    The default length of 12 with the a-z, A-Z, 0-9 character set returns
    a 71-bit value. log_2((26+26+10)^12) =~ 71 bits
    """
    valid_key_chars = string.ascii_letters + string.digits
    return ''.join(random.sample(valid_key_chars, length))
